South America

Tires tame soils

in a sodden season

James Sapsed, professional farmer, UK

Swapping from a crawler to a tyred tractor helped a Herts farm get drilled up in good time last autumn, but advice on pressures and weights was crucial to getting the performance required from its new machine.

Grip and flotation aren’t necessarily the preserve of crawlers, suggests the experience of a north Hertfordshire farming business where a switch back to a wheeled machine for one of its two main cultivation tractors has resulted in greater versatility with minimal compromise to field performance. Correct tyre and machine set-up, though, are central to getting comparable work results, according to farmer James Sapsed.

A mix of ploughing and minimum tillage are used across the 920ha (2,300 acres) of combinable crops grown on mostly clay land by James and his father Michael. For second wheats the ground is ploughed with a 12f Gregoire Besson behind a Case IH Quadtrac 500, but for first wheats and oilseed rape, a sequence of cultivation with a 6m Vaderstad TopDown followed by pressing with a 10m Vaderstad Rexius Twin is practised. A Vaderstad Rapid 8m drill is common to both systems, sowing both wheat and rape.

Having recently purchased the 500hp Quadtrac to increase ploughing and cultivation capacity, the Sapseds decided that, after a couple of seasons working the two machines alongside each other and having moved away from a trailed sprayer to a self-propelled machine, they could not justify also renewing their existing sixyear- old 320hp AGCO Challenger MT765, which had been used primarily for top work, cultivating and pressing on land initially moved by the Quadtrac and plough or TopDown, the Case IH machine then switching to the drill. Greater versatility was also required from the secondary machine, which led to the Sapseds deciding to replace the Challenger with a wheeled tractor.

“We had to decide not only which wheeled tractor to go for, but also what wheel and tyre equipment to equip it with,” says James Sapsed. “Ultimately we chose a Fendt 936. Given that it would be performing many of the same tasks as its predecessor, we were keen to maximise the amount of ground contact that could be achieved with the tractor when compared with the tracklayer, and so sought advice on the best wheels and tyres with which to equip it.

“We knew that Trelleborg had developed its TM900 tyre in conjunction with Fendt, and talked with Neil Sharman at Trelleborg about the best size and arrangement for the work we wanted the tractor to do.” His advice was to go for a taller tyre rather than a wider profile, his figures showing that 710/75 R42 tyres would actually be much more suitable than 800mm section tyres, allowing more wheel weight to be added and putting more cleats in contact with the ground.

“We also looked at 900s, but Neil advised that, as maximum pulling power was our main aim, if dualled up and paired with 600/70 R34s on the front, the 710s would be the best option for both traction and flotation. With most of our land in a block, road travel isn’t significant, and having gone from a crawler, we wanted to maintain as much grip as possible. This way we have the ground contact we want, and can weight the tractor up for primary cultivations, yet still have the convenience of being able to remove weight for secondary cultivations and drilling, and convert the tractor back to a 2.7m-wide machine for road work.”

Upon delivery, a visit was arranged to help set up the tractor and its tyres for best performance, with its axle weights measured to ensure it was properly ballasted.

“Neil showed us that if you’ve got good tyres and the tractor is weighted right, then a wheeled machine can do just as good a job as a crawler in terms of output and fuel use,” says James. “And with the long footprint of the 710 TM900s, we get more tread for our money.

“With Neil’s help we found that, when ploughing on land with our seven-furrow Gregoire Besson, we could put more lugs on the ground and vastly improve grip and performance by reducing pressures from 24psi (1.65 bar) for road work to 17- 18psi (1.17-1.24 bar) in the field, and for low-speed movement between fields we could travel without reinflation. For topwork with duals, we can reduce pressures further than that, down to 10psi (0.69 bar) all-round, giving the tractor a really light footprint.

“Road travel is usually no more than five miles maximum, and with most of our land within the home block, escorting a wide tractor still makes more sense than running a second crawler. Last season it worked with our chaser bin in summer before switching to the plough and then being dualled up for pressing, spring tining and drilling. While it wasn’t the intention to drill with the tractor, last year it sometimes proved just too wet for the Quadtrac as we struggled to get the seed in the ground behind the tracks, but we were able to keep a bit of tilth with the drill behind the Fendt on the duals. The crawler was only useful to us in the autumn, but we make use of the tractor all year round.”